季铵盐型双子表面活性剂16-4-16聚集状态的NMR研究

核磁共振弛豫，自扩散以及2D NOESY谱研究结果表明：双子表面活性剂16-4-16溶液在形成胶束的过程中，联结基团及其邻近的碳氢链质子形成胶束的壳层，而距离离子头较远的疏水质子位于胶束的内部. 与对应的单链的表面活性剂CTAB相比，其分子运动更受限制. 2D NOESY谱显示联接基团及临近的碳氢链的质子间有较强的交叉峰，表明形成胶束时，分子在联结基团附近堆积的较为紧密. 由2D NOESY谱计算得到的质子间距与HYPERCHEM模拟值有偏差，表明这些强交叉峰是分子间相互作用的结果，并且对应质子对在双子表面活性剂16-4-16分子中位于邻近的区域. 因此我们推测，双子表面活性剂16-4-16分子在球形胶束中形成特殊的排列方式.

NMR Investigation of Quaternary Ammonium Dimeric Surfactant C16-4-C16·2Br Micelles

Conformation of Gemini 16-4-16 in heavy water solutions at concentrations close to the critical micellar concentration (cmc) was studied by NMR relaxation, self-diffusion and two-dimensional nuclear Overhauser enhancement spectroscopy (2D NOESY). In forming micelles, the protons of the spacer group and a part of hydrophobic protons next to the polar head group are involved in the surface layer of the micellar core. The hydrophobic protons away from the polar head group are situated internal in the micellar core. The motion of the molecules are relatively more restricted than their monomeric homologue CTAB. 2D NOESY experiments show cross peaks between the protons in or close to the spacer group. The inter-proton distances thus calculated show deviation from those of the intra-molecular ones, calculated by HYPERCHEM. Therefore, inter-molecular interaction is responsible for these strong cross peaks. The corresponding proton pairs are in near vicinity. Accordingly we postulate a special arrangement of the molecules in the spherical 16-4-16 micelles.